<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>404</title>
</head>
<body>
<div class="container">
    <span>404</span>
</div>
</body>
<style>
.container{
    width:1200px;
    height: 450px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size:45px
}
</style>
</html>